In tubing arrangements for offshore facilities, it is often desirable to be able to prevent sea water from entering the tubing arrangement, or from passing a specific point in the tubing arrangement. In particular, it may be desirable to prevent rush of sea water into such tubing arrangements. Attempts have previously been made to solve this problem.
U.S. Pat. No. 6,003,873 discloses a method and a device for sealing the entrance of an elongated element into the lower end of an offshore tube. A plug-like device is arranged on the element, a predetermined length of the element is pulled into the tube, and the plug is fixed on the element surface at the bellmouth entrance of the tube. The outer diameter of the plug is somewhat smaller than the inner diameter of the tube. Expandable foam is injected to a space between the outer surface of the plug and the inner surface of the tube in order to substantially fill the space.
The sealing device disclosed in U.S. Pat. No. 6,003,873 can only be mounted at a bellmouth of an offshore tube. Thus, it can not be used for providing sealing in any other position along the tube. Furthermore, it is not possible to remove or replace the sealing device, e.g., in case repair or maintenance of the tube is required. Finally, it is necessary to inject the expandable foam immediately after the elongated element (e.g. a cable) is positioned in the tube. This may be difficult to fulfil when the tubing is positioned at an offshore site.
U.S. Pat. No. 5,765,834 discloses a sealing device for sealing off an elongated body, such as a cable, pipe or umbilical, at its entrance to an aperture of an apparatus, such as an offshore J-tube. The sealing device consists of two substantially identical parts or halves which are hinged together along an axis substantially parallel to the axis of the elongated body, each half comprising a centralizer part, a sealing part and tensioning parts. The tensioning parts are capable of pressing the sealing parts into sealing contact against the elongated body, against the inner surface of the J-tube and against the centralizing means. The pressure means may consist of tensioning rods with nuts. By tightening the nuts, the seal is compressed and squeezed between the centralizer and the holding device.
The sealing device of U.S. Pat. No. 5,765,834 is relatively complicated. Furthermore, it is necessary to operate the tensioning part after the elongate element has been positioned in the tube. In the case that the tube is arranged at an offshore facility, this has the consequence that the use of divers is required for this task. This adds considerably to the installation costs. Finally, the sealing device of U.S. Pat. No. 5,765,834 can only be positioned at the entrance opening of the tube, since positioning the sealing device in another position would prevent operation of the tensioning parts.